Ok, the main.log says:
:info:configure dyld: Library not loaded: /opt/local/lib/libncurses.5.dylib
:info:configure Referenced from: /opt/local/lib/libreadline.6.dylib
ncurses has already been upgraded to version 6, but your readline is still using ncurses 5. You can fix the problem by upgrading readline first, then upgrading texinfo.
texinfo itself doesn't require readline. But texinfo does require awk for this part of the configuration. The texinfo port doesn't declare a dependency on awk, because little text-processing utilities like awk, sed and grep are already installed as a part of OS X, and those versions are usually good enough. However, you already have the gawk port installed, so texinfo used that, but gawk uses readline.
